Conventionally, there have been proposed pressure detection devices that measure a pressure of a fluid flowing in a blood circuit used for dialysis, apheresis, Continuous Renal Replacement Therapy (CRRT), or the like, without having a chamber or a branch tube. Extracorporeal circulation of blood in heart surgery, emergency medical care, or the like needs various treatments, thereby increasing the number of circuits and devices. However, a space where the devices are located and a space where the located devices are used are limited. Therefore, such devices for heart surgery, emergency care, and the like which are utilized especially in emergency cases are desired to be easily handled. From this viewpoint, a diaphragm pressure sensor has been disclosed to easily measure a pressure of a fluid such as blood flowing in an extracorporeal circulation circuit.
For example, a pressure detection device used in devices for extracorporeal blood treatments has been disclosed to (i) be applied with a pressure of a fluid via a diaphragm that is provided at a surface of a tube channel in parallel to a direction of flowing the fluid, and (ii) detect, by a distortion gauge, a vertical movement of a presser pressed on the diaphragm as a power, and (iii) calculates a pressure value from the power based on an area applied with the pressure (refer to Patent Reference 1, for example). This pressure detection device is connected, as a cassette body, to a dedicated device.
Furthermore, a pressure detection station used in apheresis systems has been disclosed to (i) be applied with a pressure of a fluid via a diaphragm that is provided at a surface of a tube channel in parallel to a direction of flowing the fluid, and (ii) detect, by a distortion gauge, a vertical movement of a presser pressed on the diaphragm as a power, and (iii) calculates a pressure value from the power based on the power into a pressure value by calculation based on an area applied with the pressure (refer to Patent Reference 2, for example). This pressure detection station is connected to a dedicated device.
Still further, a liquid pressure detection structure has been disclosed to have (i) a tube body that is expanded and shrunk, (ii) a detection unit that detects an amount of the expanding and shrinking, and (iii) a joining unit that connects the tube body with the detection unit by easily installing and removing the detection unit in/from the tube body (refer to Patent Reference 3).
For these conventional diaphragm pressure sensors, a magnetic joining method has been conceived for easily joining and separating between the diaphragm and the sensor by freely installing and removing the sensor in/from the diaphragm. For examples of the joining method, the Patent Reference 2 and the Patent Reference 3 disclose technologies of joining a sensor to a diaphragm using a magnetic force.
[Patent Reference 1] Japanese Unexamined Patent Application Publication No. 2002-257656
[Patent Reference 2] Japanese Unexamined Patent Application Publication (Japanese Translation of PCT International Application) No. 2002-513321
[Patent Reference 3] Japanese Examined Patent Application Publication No. 8-33332